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Baxter J Sen N Martínez VL De Carandini ME Schvartzman JB Diffley JF Aragón L 《Science (New York, N.Y.)》2011,331(6022):1328-1332
DNA topoisomerase II completely removes DNA intertwining, or catenation, between sister chromatids before they are segregated during cell division. How this occurs throughout the genome is poorly understood. We demonstrate that in yeast, centromeric plasmids undergo a dramatic change in their topology as the cells pass through mitosis. This change is characterized by positive supercoiling of the DNA and requires mitotic spindles and the condensin factor Smc2. When mitotic positive supercoiling occurs on decatenated DNA, it is rapidly relaxed by topoisomerase II. However, when positive supercoiling takes place in catenated plasmid, topoisomerase II activity is directed toward decatenation of the molecules before relaxation. Thus, a topological change on DNA drives topoisomerase II to decatenate molecules during mitosis, potentially driving the full decatenation of the genome. 相似文献
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Chris M. C. Woods Philip J. James Graeme A. Moss Johnny Wright Sten Siikavuopio 《Aquaculture International》2008,16(1):49-68
We compared the gonad-enhancing effects of two diets (NIWA and NIFA diets) in two size classes of sea urchins (Evechinus chloroticus): small and large urchins with a test diameter of 75.6 ± 1.2 mm and 93.8 ± 0.5 mm, weighing 174.8 ± 7.9 g and 315 ± 5.6 g,
respectively. After eight weeks being fed prepared diets, urchin gonad index (GI) had significantly surpassed that of the
initial and final samples of wild urchins. Urchins in the NIWA/small treatment had a larger GI than the NIFA/small and NIFA/large
treatments. The NIWA/large treatment had a larger GI than the NIFA/large treatment. The overall percentage increase in GI
for the NIWA/small, NIWA/large, NIFA/small and NIFA/large treatments were 183%, 135%, 132% and 85%, respectively. In terms
of gonad colour (CIELAB), there were no significant differences in gonad redness (a*) or yellowness (b*) between experimental
treatments, but there was a significant difference in gonad lightness (L*) with small urchins fed both diets having lighter-coloured
gonads than the large urchins fed both diets. Sensory assessment of gonads revealed that gonads from small urchins fed both
diets were rated as being of better colouration and more uniform in colour than gonads from large urchins. Gonads of urchins
fed the NIFA diet were rated as being less bitter and of better overall taste than gonads from urchins fed the NIWA diet.
This study shows that feeding prepared diets to E. chloroticus can significantly increase gonad yield but that different diets can affect the magnitude of GI increase and the taste of
gonads, and that smaller urchins appear more suitable for gonad enhancement. 相似文献
336.
Ruth Callaway Andrew P. Shinn Suzanne E. Grenfell James E. Bron Gavin Burnell Elizabeth J. Cook Margaret Crumlish Sarah Culloty Keith Davidson Robert P. Ellis Kevin J. Flynn Clive Fox Darren M. Green Graeme C. Hays Adam D. Hughes Erin Johnston Christopher D. Lowe Ingrid Lupatsch Shelagh Malham Anouska F. Mendzil Thom Nickell Tom Pickerell Andrew F. Rowley Michele S. Stanley Douglas R. Tocher James F. Turnbull Gemma Webb Emma Wootton Robin J. Shields 《水产资源保护:海洋与淡水生态系统》2012,22(3):389-421
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